Not possible to use custom methods in paths

[seba-ban]

Describe the bug
It seems that it's not possible to use custom methods in endpoint paths.

To Reproduce

@api({ name: "test", version: "1" })
class Api {}

@endpoint({
  method: "POST",
  path: "/items/:id:run",
})
class RunItem {
  @request
  request(
    @pathParams
    pathParams: {
      id: string;
    }
  ) {}

  @response({ status: 202 })
  successfulResponse() {}
}

Running spot generate --contract src/contract/api.ts --language yaml --generator openapi3 --out tst/ throws an error:

Error: endpoint path dynamic components must have a corresponding path param defined in @request. Violating path components: id:run

I think it's because this function for the example above will return ['id:run'] and this string is then expected to be defined in pathParams.

Expected behavior
To generate openapi spec without an error.

Desktop:

• OS: Ubuntu
• Node version: v14.17.0
• Spot version: 1.9.0